1. Field of the Invention
The present invention relates to a method of limiting communication access between wireless LAN terminals.
2. Description of the Related Art
Some conventional inter-LAN repeaters for use in wireless LAN access point installations for regenerating signals between wired LANs and wireless LANs are capable of dispensing with unwanted repeating operation for unstudied stations in the wireless LANs thereby to greatly reduce the load on transmission paths in the wireless LANs which have a low transmission rate (see, for example, Patent Document 1 below).
There is known a wireless LAN system in which an access point as a control terminal device receives a frame destined outside a cell and makes a response representative of a reception success or a reception failure for efficient communications with a wireless terminal device in another cell or a wired terminal device connected to a wired transmission path (see, for example, Patent Document 2 below).
According to another known wireless LAN system, a control device stores connection permitting conditions for mobile stations (wireless LAN terminals) in respective access points, determines whether a connection request from a mobile station matches any of the stored connection permitting conditions, and allows the mobile station to be connected only if the connection request matches a stored connection permitting condition (see, for example, Patent Document 3 below).
FIG. 1 of the accompanying drawings shows a sequence of operation of a conventional wireless LAN that is made up of only existing devices. Address information allocated to terminals in the conventional wireless LAN shown in FIG. 1 is as follows:
Wireless LAN terminal 1:                IP address=192.168.1.1        Subnet mask=255.255.255.0        Subnet=192.168.1        Default gateway=192.168.1.254 (=access limiter);        
Wireless LAN terminal 2:                IP address=192.168.1.2        Subnet mask=255.255.255.0        Subnet=192.168.1        Default gateway=192.168.1.254 (=access limiter);        
Wired terminal:                IP address=192.168.0.1        Subnet mask=255.255.255.0        Subnet=192.168.0        Default gateway=192.168.1.254 (access limiter).        
In FIG. 1, the wireless LAN terminals have identical subnets. In reply to an ARP request that flows from wireless LAN terminal 1 (604) to wireless LAN terminal 2 (605) prior to packet transmission, wireless LAN terminal 2 (605) directly returns a response. Therefore, data are returned from a wireless LAN access point, and communications are made without through access limiter 602.
According to conventional communications between wireless LAN terminals, because
(1) identical subnets are allocated to wireless LAN terminals, and
(2) packets designed for the identical subnets are sent not through a default gateway, data flow from wireless LAN terminal 1 to the access point to wireless LAN terminal 2, and hence an access limiting function cannot be provided unless the access point is modified.
Patent Document 1: Japanese laid-open patent publication No. 8-274804;
Patent Document 2: Japanese laid-open patent publication No. 10-164073; and
Patent Document 3: Japanese laid-open patent publication No. 11-55286.
The above conventional systems suffer from a problem as to how communications between wireless LAN terminals are to be seized with respect to band limitation and charging for pay services such as hot spots or the like.
Pay services such as hot spots or the like, which should be provided inexpensively unlike cellular phone services, do not have a lot of money to spend for constructing a network of their own. It is considered customary for those services to employ wireless LAN access points that can be purchased ordinarily, e.g., access points that are commercially available for about 30,000 yen, rather than customized access points. If hot spot services are to begin at locations where such inexpensive access points have already been installed (they cannot easily be removed as they are generally incorporated in buildings), it is the normal practice to use the existing equipment. However, since an inexpensive access point is not expected to be used by hot spot services, data sent from a wireless LAN terminal to another wireless LAN terminal are returned from the access point.
When communications such as ftp communications are performed between wireless LAN terminals that are not designed for use with hot spot services, the entire wireless band is consumed, causing trouble to the hot spot services. Basically, hot spot services need to limit communications between wireless LAN terminals.
Attention is being paid to hot spot services using wireless LANs. If an existing wireless LAN access point is employed, then since the access point returns data, data communications started between wireless terminals tend to occupy 100% of the wireless band in an area which cannot be controlled by the service provider, resulting in the danger of a failure to provide the services.
Consequently, it is necessary to solve the problem as to what should be done to prevent packets transmitted between wireless LAN terminals from being returned from an access point.